Fracture Resistance of Molars with Class II MOD Cavities Restored with CAD/CAM Ceramic Onlays: Impact of Deep Marginal Elevation

Objective: This study evaluated the effect of deep marginal elevation (DME) using an ion-releasing material, resin-modified glass ionomer, and nano-hybrid flowable composite on the fracture resistance of molars with Class II MOD cavities restored with CAD/CAM ceramic onlays. Materials and Methods: Fifty molar teeth were randomly assigned to one of five groups (n=10/group): Enamel (EN), Cementum (CE), Cention forte (CF), Tetric-N flow (TF), and Resin modified glass ionomer (RM) groups. Specimens were prepared for a standard MOD cavity with margins located 2 mm below the CEJ for CF, RM, TF, and CE groups, while the EN group had margins located 1 mm above the CEJ. DME was used to elevate the margins to 1 mm above the CEJ. For the CE group, the ceramic onlay was placed without DME. Standardized IPS e.max ZirCAD ceramic onlays were fabricated with CAD/CAM and bonded on all specimens with G-cem Capsule. All teeth were subjected to 10,000 cycles of thermocycling (5°C/55°C). The fracture resistance of each group was measured using a universal testing machine. Data was statistically analyzed using a one-way ANOVA test. Results: Fracture strength values were subjected to one-way ANOVA revealed statistically non-significant differences among experimental groups (p=0.08). Conclusions: Within the parameters of this study, the materials had a non-significant difference in fracture resistance. Therefore, collective findings suggest that these materials were suitable for DME.